(1) Field of Invention
The present invention relates to a hydraulic cement composition. More particularly, the present invention relates to a hydraulic cement composition which shows a markedly excellent fluidity with a small normal consistency and also shows excellent water impermeability, fire resistance, strength and weatherability after hardening and which is very valuable as a binder, sealant or solidifying agent for various materials and also as a molding material.
(2) Description of the Prior Art
Hydraulic cements such as Portland cement have been widely used as the cement composition. However, a normal consistency of 26 to 35% is necessary for imparting a sufficient hardenability to these known cement compositions. It is known that the mechanical strength or denseness of a hydraulic cement is greatly influenced by the normal consistency, and since conventionl Portland cement has a relatively large normal consistency, a hardened product thereof is relatively poor in the flexural strength and the like and its water permeability is relatively high. Moreover, a known unhardened aqueous composition of Portland cement is poor in the fluidity though the normal consistency is large, and it is difficult to fill this composition in fine voids or the like.
Recently, there is adopted a method in which a concentrated waste liquid discharged from the vicinity of a nuclear reactor or an ion exchange resin used for the treatment of this waste liquid is dried and is packed in a vessel in the state solidified by a solidifying agent and the sealed vessel is stored or discarded. The solidifying agent to be used in this method should satisfy various requirements. First of all, since this solidifying agent is exposed to radioactive rays, it should have such a property that it is not substantially deteriorated by radioactive rays. From this viewpoint, use of an inorganic solidifying agent is preferred. Furthermore, this solidifying agent should be excellent in the resistance to permeation of water, the mechanical strength and the weatherability. Moreover, the solidifying agent should have such a long pot life that the filling operation or the like can be performed conveniently, and the solidifying agent should have such a fluidity that the solidifying agent can uniformly flow in the vessel and can be uniformly filled in any part of the vessel. Still further, it is important that the volume of the waste per unit volume of the vessel, that is, the volume reduction ratio, should be increased. For this purpose, the solidifying agent should be used in an amount as small as possible.